1. Field of the Invention
The invention relates to oil-soluble hydrocarbyl substituted bicyclic oxazolidines, i.e. 1-aza-3,7-dioxabicyclo [3.3.0]oct-5-yl methyl alcohols, particularly those substituted in the 2 and/or 8 positions with a group preferably of at least 3 carbon atoms, which alcohols are derived from the reaction of an aldehyde and tris (hydroxymethyl) aminomethane.
These oil-soluble compounds have utility as additives for functional fluids, preferably mineral oil compositions and systems including automatic transmission fluids, lubricating oils and synthetic lubricants.
2. Description of the Prior Art
Lubricant additives derived from a reaction with tris (hydroxymethyl) aminomethane (THAM) are well known and include U.S. Pat. Nos.: 3,576,743; 3,632,511; 3,679,428; and 4,049,564 and United Kingdom Specification Nos.: 809,001 and 984,409.
In British Patent No. 564,506, the condensation product of THAM and formaldehyde, i.e. 1-aza-3,7-dioxabicyclo [3.3.0]oct-5-yl methyl alcohols, is said to react with fatty acids to give unstable ester products which are useful as drying oils.
U.S. Pat. No. 3,738,992 discusses esters of 1-aza-3,7-dioxabicyclo[3.3.0]oct-5-yl methyl alcohol as antifoam agents and lubricant additives, especially for aqueous textile lubricants.
U.S. Pat. No. 3,843,726 teaches that azadioxabicyclo-octane compounds, e.g. 1-aza-5-hydroxymethyl-2,8-diphenyl-3,7-dioxabicyclo (3.3.0) octane [see Example 1], (prepared by reaction of THAM and an aldehyde) can be halogenated to provide an intermediate useful for the preparation of an antiradiation drug.
Bicyclic oxazolidines are disclosed to be produced from an aldehyde and THAM in a publication entitled Chemistry and Use of Aminohydroxy Compounds by Commercial Solvents Corporation, N.Y. N.Y.
In prime movers utilizing a functional fluid for power transmission, including hydraulic fluids and automatic transmission fluids, it is generally necessary to remove heat generated during the operation of the functional fluid. One approach involves passing said fluid through a heat exchanger utilizing copper as a structural part or in a brazing mixture joining structural parts, e.g. the automatic transmission fluid of a car is frequently controlled by a heat exchanger located in the car radiator and immersed in the radiator coolant. Operational corrosion of the copper results in mechanically catastrophic intermixing of the functional fluid and radiator coolant (ethylene glycol) and/or loss of said fluid. It is necessary to reduce the copper corrosiveness of said fluid circulating in contact with copper so as to extend the operational lifetime of the prime mover or other mechanical device employing said fluid. One approach is to incorporate a compatible anti-copper corrosion additive into said fluid.
It is an object to this invention to provide an anti-copper-corrosion additive for functional fluids, preferably for automatic transmission fluids.